Three-piston ankle mechanism of a legged robot and associated control system

Abstract

An example robot includes a first actuator and a second actuator connecting a first portion of a first member of the robot to a second member of the robot. Extension of the first actuator accompanied by retraction of the second actuator causes the first member to roll in a first roll direction. Retraction of the first actuator accompanied by extension of the second actuator causes the first member to roll in a second roll direction. A third actuator connects a second portion of the first member to the second member. Extension of the third actuator accompanied by retraction of both the first and second actuators causes the first member to pitch in a first pitch direction. Retraction of the third actuator accompanied by extension of both the first and second actuators causes the first member to pitch in a second pitch direction.

What is claimed is: 
     
       1. A robotic leg comprising:
 a ground-engaging foot member having a longitudinal axis extending from a toe portion of the ground-engaging foot member to a heel portion of the ground-engaging foot member; 
 an ankle member coupled to the ground-engaging foot member along the longitudinal axis of the ground-engaging foot member by a first coupling; 
 a shin member coupled to the ankle member by a second coupling; and 
 a first actuator extending along a length of the shin member toward the foot member, the first actuator coupled to the foot member by a third coupling, 
 wherein the first coupling is located closer to a ground-engaging surface of the ground-engaging foot member than the second coupling. 
 
     
     
       2. The robotic leg of  claim 1 , wherein the third coupling is located at a position between a medial side of the ground-engaging foot member and a lateral side of the ground-engaging foot member. 
     
     
       3. The robotic leg of  claim 1 , wherein:
 the first coupling provides a roll axis of rotation for the ankle member to roll toward a medial side or a lateral side of the foot member; and 
 the second coupling provides a pitch axis of rotation for the ankle member to pitch the toe portion of the foot member towards the shin member or away from the shin member. 
 
     
     
       4. The robotic leg of  claim 1 , wherein a first axis along a length of the first coupling is perpendicular to a second axis along a length of the second coupling. 
     
     
       5. The robotic leg of  claim 1 , wherein a second axis along a length of the second coupling is parallel to a third axis along a length of the third coupling. 
     
     
       6. The robotic leg of  claim 1 , wherein the ankle member is centrally disposed between a medial side and a lateral side of the ground-engaging foot member. 
     
     
       7. The robotic leg of  claim 1 , further comprising:
 a second actuator coupled to the foot member by the third coupling, 
 wherein actuation of one of the first actuator or the second actuator rolls the foot member laterally. 
 
     
     
       8. The robotic leg of  claim 1 , further comprising a second actuator coupled to the ankle member by a fourth coupling, the fourth coupling disposed at a heel-adjacent portion of the ankle member. 
     
     
       9. The robotic leg of  claim 1 , further comprising:
 a second actuator coupled to the foot member by the third coupling; and 
 a third actuator coupled to the ankle member by a fourth coupling, the fourth coupling disposed at an end of the ankle member opposite the third coupling. 
 
     
     
       10. The robotic leg of  claim 1 , wherein the shin member couples to the ankle member along an outer surface of the ankle member between a medial side and a lateral side of the ground-engaging foot member. 
     
     
       11. A robotic leg comprising:
 a ground-engaging foot member having a longitudinal axis extending from a toe portion of the ground-engaging foot member to a heel portion of the ground-engaging foot member; 
 an ankle member coupled to the ground-engaging foot member along the longitudinal axis of the ground-engaging foot member by a first coupling, the ankle member axially rotatable about the first coupling; 
 a shin member coupled to the ankle member by a second coupling, the shin member comprising at least one elongated actuator chamber extending along a length of the shin member; and 
 a first actuator partially housed within the at least one elongated actuator chamber, the first actuator comprising a piston slidably received within the at least one elongated actuator chamber, the first actuator extending from the shin member and coupling to the foot member by a third coupling. 
 
     
     
       12. The robotic leg of  claim 11 , wherein the third coupling is located at a position between a medial side of the ground-engaging foot member and a lateral side of the ground-engaging foot member. 
     
     
       13. The robotic leg of  claim 11 , wherein:
 the first coupling provides a roll axis of rotation for the ankle member to roll toward a medial side or a lateral side of the foot member; and 
 the second coupling provides a pitch axis of rotation for the ankle member to pitch the toe portion of the foot member towards the shin member or away from the shin member. 
 
     
     
       14. The robotic leg of  claim 13 , wherein the roll axis is closer to a ground-engaging surface of the ground-engaging foot than the pitch axis. 
     
     
       15. The robotic leg of  claim 11 , wherein a first axis along a length of the first coupling is perpendicular to a second axis along a length of the second coupling. 
     
     
       16. The robotic leg of  claim 11 , wherein a second axis along a length of the second coupling is parallel to a third axis along a length of the third coupling. 
     
     
       17. The robotic leg of  claim 11 , wherein the ankle member is centrally disposed between a medial side and a lateral side of the ground-engaging foot member. 
     
     
       18. The robotic leg of  claim 11 , further comprising:
 a second actuator coupled to the foot member by the third coupling, 
 wherein actuation of one of the first actuator or the second actuator rolls the foot member laterally. 
 
     
     
       19. The robotic leg of  claim 11 , further comprising a second actuator coupled to the ankle member by a fourth coupling at a heel-adjacent portion of the ankle member. 
     
     
       20. The robotic leg of  claim 11 , further comprising:
 a second actuator coupled to the foot member by the third coupling; and 
 a third actuator coupled to the ankle member by a fourth coupling, the fourth coupling at an end of the ankle member opposite the third coupling. 
 
     
     
       21. The robotic leg of  claim 11 , wherein the shin member couples to the ankle member along an outer surface of the ankle member between a medial side and a lateral side of the ground-engaging foot member.